In recent years the environmental impact of constructing and maintaining waterways of all kinds, landfills and drainage has been receiving a great deal of public attention as well as being the subject of extensive governmental regulations. All present forms of dredging and the chemical and mechanical removal of aquatic growths are rapidly becoming unacceptable. Additionally, the cost thereof has increased to an extent that has curtailed proper maintenance resulting in material restriction of navigation and increasing the possibility of widespread flooding due to reduced drainage flow.
Dredging of waterways, channels, ditches and the like has taken many forms. The spoil has been either cast along one or both sides of the dredged area in piled berm at a distance permitted by the length of a boom, trucked or barged to a remote point or pumped to a remote spoil pond, landfill or the like all to the detriment of the environment. In most cases it has not been practical or possible to grade the spoil to avoid unsightly and detrimental land elevation or bars and shoals restricting navigation and natural waterflow, or destructive smothering of fragile marsh lands, etc.
Present dredging practices are particularly harmful to marine life cycles when carried out in tidal waters, salt marshes and the like. Although regulations have been enacted limiting the permitted increase in elevation adjacent dredging operations, it has not been possible to conform to such regulations in many areas and they are being ignored.
Dredging heads capable of supplying a pumpable slurry from the swath area cut by the head are well known. The width of the head may be less than the barge or other form of floating support structure as shown in U.S. Pat. No. 3,412,862 or substantially the same width as disclosed in U.S. Pat. No. 3,962,803. Reference is also made to the applicant's U.S. Pat. No. 3,971,148 as well as to U.S. Pat. No. 3,521,387 to which it relates.
In addition to prolific aquatic plant growth increasingly stimulated by commercial and household nutrients, a continuous buildup of unconsolidated sediment takes place in most waterways and the like in the form of silt, muck, decaying vegetation, etc. Such sediment in time is superimposed upon the natural or dredged profile of the bottom of the waterway restricting and impeding navigation and rate of drainage.